Electric car explosion or, more precisely, the vapour cloud explosion(VCE)!
Photo from Qdpnews.it
We are back to talking about electric cars again, but this time we are talking about the EV explosion in an Italian city.
Nightmare night for a family from Treviso, Italy, on the night between 14 and 15 June: their electric 2020 Renault Zoe exploded while parked in their garage and was NOT being charged.
Photo from corrieredelveneto.it
The explosion of the electric car tore open the garage door where the vehicle was located, and the flames reached a Mercedes B-class that was parked outside, damaging it in turn. The explosion caused extensive property damage and damaged the neighbours’ house, but fortunately, no one was hurt. It remains to be seen what caused the explosion, which could have had dramatic consequences if it had happened in broad daylight and in a busier area.
All that is known is that the car was loaded at a charging point at the LIDL supermarket in the afternoon when the maximum outside temperature was 27°C. When the outside temperature is 25°C, the asphalt temperature reaches 50°C. When the air temperature rises, so does the asphalt temperature: 30°C outside equals 55°C, and 32°C outside equals 60°C on asphalt. But the Renault Zoe 2020 has air battery pack cooling that should start when, when charging, the pack temperature exceeds the limit!
It is worth mentioning that Renault Zoe 2019 has a recall: “A manufacturing defect in the battery can cause a short circuit. This can cause overheating and damage to electrical systems, increasing fire risk.”.
Could this also be a problem with the Renault Zoe of Treviso? Maybe or maybe not!
The fire brigade suspects that the car’s battery went into a silent thermal runaway and that gases were released and accumulated inside the car, culminating in its explosion during the night.
What is the thermal runaway?
Lithium-ion battery thermal runaway occurs when a battery cell short-circuits and starts to heat up uncontrollably. Once the battery becomes unstable, chemical reactions produce heat and toxic & flammable gases: heat speeds up these reactions, producing more heat and more gases.
Credits prof. Paul Christensen, Newcastle University
On the evfiresafe.com website, they explain very well what is a thermal runaway and how it is produced.
Electric car explosion – risk rate
According to a survey done between 2010 and 2020 by the evfiresafe.com website, “EV fires overall are very rare, but EV vapour cloud explosions (VCE)(aka EV car explosion!) are even less likely, involved in just 10.77% of all EV battery fire incidents. Our research identified & verified fourteen (14) EV explosion incidents since 2010 – that’s from a global market of 10 million EVs in operation at the end of 2020.”.
We can summarise the results in the following image:
- The website specifies that: “Obviously, underground & enclosed spaces present the greatest cause for concern, primarily due to escape & evacuation, confinement of toxic gases near members of the public & access for emergency appliances & people. Additionally, some early testing that indicates battery fires may have the potential to cause issues with building structural integrity.”.
The explosion of the electric car in Treviso amply demonstrated this.
We will only know for sure what happened in Treviso after the fire brigade finishes its investigation. We will come back with updates on this topic
